class_docstr: A key/value pair with polymorphic value storage.
  
  The class which is mapped should indicate typing information
  within the "info" dictionary of mapped Column objects; see
  the AnimalFact mapping below for an example.
code: def __repr__(self):
      return "<%s %r=%r>" % (
          self.__class__.__name__,
          self.key,
          self.value,
      )
  
imports: from sqlalchemy import and_
  from sqlalchemy import Boolean
  from sqlalchemy import case
  from sqlalchemy import cast
  from sqlalchemy import Column
  from sqlalchemy import create_engine
  from sqlalchemy import event
  from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy import literal_column
  from sqlalchemy import null
  from sqlalchemy import or_
  from sqlalchemy import String
  from sqlalchemy import Unicode
  from sqlalchemy import UnicodeText
  from sqlalchemy.ext.associationproxy import association_proxy
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.ext.hybrid import hybrid_property
  from sqlalchemy.orm import relationship
  from sqlalchemy.orm import Session
  from sqlalchemy.orm.collections import attribute_keyed_dict
  from sqlalchemy.orm.interfaces import PropComparator
  from .dictlike import ProxiedDictMixin
label_desc: Use image node_id 5 for calling the PolymorphicVerticalProperty obj's underlying member method code with example usage: obj.__repr__() and returns: unknown